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Subject: Re: 4.18rc3 TX2 boot failure with "ACPICA: AML parser: attempt to
 continue loading table after error"
To:     "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc:     "Schmauss, Erik" <erik.schmauss@intel.com>,
        "linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
References: <c49a3666-7d23-6a05-703c-1273d79a00cd@arm.com>
 <218e4339-477d-eb0d-6007-764c8e24229f@arm.com>
 <3574827.zOC4apc8e1@aspire.rjw.lan> <2264016.O8iB3BUh2s@aspire.rjw.lan>
From:   Jeremy Linton <jeremy.linton@arm.com>
Message-ID: <dc4c68bb-089c-6c99-31df-e8d3587b6029@arm.com>
Date:   Tue, 10 Jul 2018 10:04:21 -0500
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Hi,

On 07/10/2018 06:25 AM, Rafael J. Wysocki wrote:
> On Tuesday, July 10, 2018 1:13:17 PM CEST Rafael J. Wysocki wrote:
>> On Tuesday, July 10, 2018 5:44:05 AM CEST Jeremy Linton wrote:
>>> Hi,
>>>
>>> On 07/09/2018 04:28 PM, Rafael J. Wysocki wrote:
>>>> On Mon, Jul 9, 2018 at 10:45 PM, Jeremy Linton <jeremy.linton@arm.com> wrote:
>>>>> Hi,
>>>>>
>>>>> First thanks for the patch..
>>>>>
>>>>> On 07/08/2018 04:14 AM, Rafael J. Wysocki wrote:
>>>>>>
>>>>>> On Monday, July 2, 2018 11:41:42 PM CEST Jeremy Linton wrote:
>>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> I'm experiencing two problems with commit 5088814a6e931 which is
>>>>>>> "ACPICA: AML parser: attempt to continue loading table after error"
>>>>>>>
>>>>>>> The first is this boot failure on a thunderX2:
>>>>>>>
>>>>>>> [   10.770098] ACPI Error: Ignore error and continue table load
>>>>>
>>>>>
>>>>> [trimming]
>>>>>
>>>>>>> ]---
>>>>>>>
>>>>>>> Which does appear to be the result of some bad data in the table, but it
>>>>>>> was working with 4.17, and reverting this commit solves the problem.
>>>>>>
>>>>>>
>>>>>> Does the patch below make any difference?
>>>>>>
>>>>>> ---
>>>>>>     drivers/acpi/acpica/psobject.c |    3 +++
>>>>>>     1 file changed, 3 insertions(+)
>>>>>>
>>>>>> Index: linux-pm/drivers/acpi/acpica/psobject.c
>>>>>> ===================================================================
>>>>>> --- linux-pm.orig/drivers/acpi/acpica/psobject.c
>>>>>> +++ linux-pm/drivers/acpi/acpica/psobject.c
>>>>>> @@ -39,6 +39,9 @@ static acpi_status acpi_ps_get_aml_opcod
>>>>>>           ACPI_FUNCTION_TRACE_PTR(ps_get_aml_opcode, walk_state);
>>>>>>           walk_state->aml = walk_state->parser_state.aml;
>>>>>> +       if (!walk_state->aml)
>>>>>> +               return AE_CTRL_PARSE_CONTINUE;
>>>>>> +
>>>>>
>>>>>
>>>>> Well this seems to avoid the crash, but now it hangs right after on the
>>>>> "Ignore error and continue table load" message.
>>>>
>>>> Well, maybe we should just abort in that case.
>>>>
>>>> I'm wondering what happens if you replace the return statement in the
>>>> patch above with
>>>>
>>>> return_ACPI_STATUS(AE_AML_BAD_OPCODE)
>>>
>>> Yes, that is where I went when I applied the patch but I used
>>> AE_CTRL_TERMINATE, which terminates the loop in acpi_ps_parse_loop() and
>>> that appears to successfully finish/terminate the initial parsing pass.
>>> But, it then crashes in acpi_ns_lookup called via the
>>> acpi_walk_resources sequences that goes through ut_evalute_object() due
>>> to the path/scope_info->scope.node being ACPI_ROOT_OBJECT (-1) and
>>> bypassing the null check. Adding a ACPI_ROOT_OBJECT check as well as the
>>> null checks in acpi_ns_lookup results in a successful boot. Tracking
>>> down how the terminate (or whatever) is leaving the info->prefix_node
>>> (in acpi_ns_evaluate) set to ROOT_OBJECT instead of null, is something I
>>> don't yet understand.
>>>
>>> Anyway, I tried Using BAD_OPCODE rather than TERMINATE and it seems to
>>> have the same basic result as PARSE_CONTINUE.
>>
>> OK, thanks!
>>
>> I evidently didn't look deep enough.
>>
>> Can you please check the patch below?
>>
>> I'm not sure if we can pass this broken state to
>> acpi_ps_complete_final_op(), so it may be necessary to return
>> an error directly when aml_op_start is NULL.
>>
>> ---
>>   drivers/acpi/acpica/psloop.c |    3 +++
>>   1 file changed, 3 insertions(+)
>>
>> Index: linux-pm/drivers/acpi/acpica/psloop.c
>> ===================================================================
>> --- linux-pm.orig/drivers/acpi/acpica/psloop.c
>> +++ linux-pm/drivers/acpi/acpica/psloop.c
>> @@ -493,6 +493,9 @@ acpi_status acpi_ps_parse_loop(struct ac
>>   		ASL_CV_CAPTURE_COMMENTS(walk_state);
>>   
>>   		aml_op_start = parser_state->aml;
>> +		if (!aml_op_start)
>> +			break;
>> +
>>   		if (!op) {
>>   			status =
>>   			    acpi_ps_create_op(walk_state, aml_op_start, &op);
>>
>> --
> 
> So maybe something like this:
> 
> ---
>   drivers/acpi/acpica/psloop.c |    3 +++
>   1 file changed, 3 insertions(+)
> 
> Index: linux-pm/drivers/acpi/acpica/psloop.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/acpica/psloop.c
> +++ linux-pm/drivers/acpi/acpica/psloop.c
> @@ -494,6 +494,9 @@ acpi_status acpi_ps_parse_loop(struct ac
>   
>   		aml_op_start = parser_state->aml;
>   		if (!op) {
> +			if (!aml_op_start)
> +				return_ACPI_STATUS(AE_AML_INTERNAL);
> +
>   			status =
>   			    acpi_ps_create_op(walk_state, aml_op_start, &op);
>   			if (ACPI_FAILURE(status)) {
> 
> 

This gets rid of the infinite loop, but its still has the problem with 
acpi_ns_lookup crashing due to -1 in the scope.node.